Scientists say a man-made "dead zone" in the Gulf of Mexico
is as big as the state of Connecticut.
The zone, which at about 13,000 sq km is the second largest
in the world but still smaller than in previous years, is so
named because it contains no oxygen, or too little, at the
Gulf floor to support bottom-dwelling fish and shrimp.
The primary cause of the annual phenomenon is excess nutrient
runoff from farms along the Mississippi River, which empties
into the Gulf, said Gene Turner, a researcher at Louisiana
State University's Coastal Ecology Institute.
The nutrients feed algae growth, which consumes oxygen when
it works its way to the Gulf bottom, he said.
"It's a poster child for how we are using and abusing our
natural resources," Turner said.
Turner said the zone has at least twice in recent years
reached the size of Massachusetts, about 21,000 sq km.
The Gulf dead zone, which fluctuates in size, is exceeded
only by a similar zone in the Baltic Sea around Finland,
The number of dead zones worldwide currently totals more than
550 and has been increasing for decades, according to a
report by Turner and Nancy Rabalais from the Louisiana
Universities Marine Consortium.
The elongated Gulf zone typically hugs the Louisiana
coastline from the Mississippi River Delta to the state's
border with Texas, and some years extending offshore of Texas
and Mississippi, Rabalais said.
The scientists said a growth in farmed land along the
Mississippi River in the 1960s began increasing pollution. In
the 1970s, levels of oxygen in parts of the Gulf fell below
the needs of bottom-dwelling fish. The zone has been
generally growing ever since.
Floods, droughts, storms and other factors affect the volume
of nutrients flowing into the Gulf and account for
year-over-year fluctuations, Turner said.
"It seems to have leveled out in size, but it could get
worse" depending on changes in pollution levels, Rabalais
The report said federal farm policy impacts the amount of
pollution in the river. Turner said corn fields, which lay
bare most of the year and leach nutrients, are one of the
biggest contributors to the problem.
A federal task force organized with river states in 2001 to
reduce nutrient runoff has had no substantial success, he